Technical Field
The present invention relates to the technical field of medical apparatuses, and particularly to a stent with a drug coating for preventing and treating restenosis and a preparation method thereof.
Related Art
At present, percutaneous coronary intervention (PCI) is a main method for treating coronary heart disease. However, due to the unclear arteriosclerotic mechanism of the coronary arteries themselves and the potential damage caused by mechanical dilatation and implantation of a metal stent, the blood vessels locally produce an inflammatory reaction and excessive healing against the damage, leading to negative vascular remodeling, migration of smooth muscle cells, and neointimal hyperplasia. In-stent restenosis (ISR) is formed after PCI, and the restenosis rate can be up to 15 to 40% after the stent implantation.
In order to prevent the formation of restenosis, the previously developed drug-eluting stent (DES), also known as drug-releasing stent, is used to carry drugs by the polymer coated on the metal stent. When the stent is placed in the intravascular lesion, a biological effect is exerted by releasing the drug by means of elution from the polymer coating under control to the vascular wall tissue, whereby the restenosis rate after PCI is significantly reduced. DES is a new milestone in the development of PCI technology.
Effective stents commonly used in the prior art include, for example, sirolimus-, paclitaxel- and other drug eluting stents, which have a reliable therapeutic effect in the prevention of restenosis after coronary artery balloon dilatation. However, these drugs inhibit the healing of injured intimal of the blood vessels after balloon dilation, thus increasing the long-term thrombotic complications. Several clinical trials and meta-analysis show that such drug-eluting stents may increase the incidence of death or myocardial infarction (in-stent thrombosis), which affects the long-term prognosis. The annual incidence of cardiac events after PCI for acute myocardial infarction is about 20%, and the incidence of restenosis after implantation of a drug eluting stent is still about 10%. In addition, such drug-eluting stents are expensive, and an imported stent costs about 20,000 RMB, which is not suitable for generalization considering China's national conditions, due to the increased medical costs and financial burden of the patients.
In view of the pathophysiologic mechanism of restenosis, drug-eluting stents with anti-thrombotic, anti-inflammatory and anti-cell migration and proliferative effects theoretically have the effect of preventing restenosis. However, the results of research on use of these drug eluting stents after PCI are undesirable, because although the drugs can reduce restenosis, some have serious toxic and side effects.